1. Field of the Invention
The present invention relates to a calibration method in a measurement of hemoglobin A1c by use of a separation analysis.
2. Description of Related Art
In the field of diabetes treatment, a special emphasis has been placed on a strict control of blood glucose values for the purpose of preventing critical complications. In particular, accuracy and precision of hemoglobin A1c (hereinafter, also referred to as “HbA1c”) level as an index in the control of blood glucose values constitutes an important factor to be monitored that can even influence the quality of diabetes treatment.
There have been considerable variations for HbA1c measuring apparatuses depending on manufactures and facilities, and there have been problems in the accuracy in HbA1c values. However, there has been a remarkable improvement in solving these problems as a result of standardization in the method of measuring the HbA1c (see ‘An Interim Report of the Committee on an Interlaboratory Standardization of HbA1c Determination’ Journal of the Japan Diabetes Society, Vol. 37, No. 3, p. 233-243, 1994 for example). Furthermore, and more recently, a guideline was established for standardizing the HbA1c value that has been expressed differently among countries. Thus, the role of system configuration in the HbA1c measurement has become more important (see ‘Japanese Guideline for reporting HbA1c results reported in IFCC units and JDS units’ Journal of Japan Society of Clinical Chemistry, Vol. 37, No. 4, p. 393-409, 2008 for example).
For a measurement of an HbA1c amount, for example, a separation analysis, an affinity measurement, an immunization measurement, an enzyme measurement and the like have been used. Apparatuses and reagents to be used exclusively for HbA1c measurements have also come into commercial use. Among them, in the field of diabetes treatment, utility of HbA1c measurement by use of the separation analysis has been extensively evaluated. For this reason, for example, apparatuses employing the separation analysis such as high pressure liquid chromatography (HPLC) have come into commercial use. Examples thereof include ADAMS A1c HA-8170 (trade name, supplied by ARKRAY, Inc. (see ‘Fundamental evaluation of HbA1c measurement using ADAMS-A1c HA-8170’ Journal of Medicine and Pharmaceutical Science, Vol. 58, No. 2, p. 355-361, 2007 for example)) and HLC-723G8 (trade name, supplied by Tosoh Corporation (see ‘Development of Tosoh Automated Glycohemoglobin Analyzer HLC-723G8’ TOSOH Research & Technology Review for example)). Each of the apparatuses is packaged with a system calibration function due to the above-mentioned reason. For the calibration method, a calibration method is employed using two calibration standards with different HbA1c values to establish two calibration data points (two-point calibration method) (see ‘Catalog of Tosoh Automated Glycohemoglobin Analyzer HLC-723G8’ (Tosoh Corporation) for example)).
Furthermore, separation analysis methods other than the HPLC method can be used. For example, HbA1c measurement technology using capillary electrophoresis is currently under development (see WO 2008/029684 and WO 2008/029685 for example).